Tadpole body size and behaviour alter the social acquisition of a defensive bacterial symbiont

Individual differences in host phenotypes can generate heterogeneity in the acquisition and transmission of microbes. Although this has become a prominent factor of disease epidemiology, host phenotypic variation might similarly underlie the transmission of microbial symbionts that defend against pathogen infection. Here, we test whether host body size and behaviour influence the social acquisition of a skin bacterium, Janthinobacterium lividum, which in some hosts can confer protection against infection by Batrachochytrium dendrobatidis, the causative agent of the amphibian skin disease chytridiomycosis. We measured body size and boldness (time spent in an open field) of green frog tadpoles and haphazardly constructed groups of six individuals. In some groups, we exposed one individual in each group to J. lividum and, in other groups, we inoculated a patch of aquarium pebbles to J. lividum. After 24 h, we swabbed each individual to estimate the presence of J. lividum on their skin. On average, tadpoles acquired nearly four times more bacteria when housed with an exposed individual compared to those housed with a patch of inoculated substrate. When tadpoles were housed with an exposed group-mate, larger and ‘bolder’ individuals acquired more bacteria. These data suggest that phenotypically biased acquisition of defensive symbionts might generate biased patterns of mortality from the pathogens against which they protect.


Recommendation? Accept with minor revision (please list in comments)
Comments to the Author(s) Royal Society Open Science Dear, Dr John Dalton, Associate Editor of Royal Society Open Science journal Here I sending my review on the Manuscript ID RSOS-191080, entitled "Tadpole body size and behavior alter the social acquisition of a defensive bacterial symbiont." The authors (Keiser et al.) details an interesting work that tested the effect of social interaction in the transmission of a microbial symbiont in the green frog tadpoles. In some host this bacterium can confer protection against infection by Batrachochytrium a lethal pathogen that cause high level of mortality in amphibians. Clearly the results present by the authors have merits to be publish. However, I think the manuscript could be improved after some revisions that I details below Sincerely yours Is not clear in the introduction if the tadpoles of green frog are social or sub-social, i.e. they form schools or only aggregate for feeding or because they select warm sites as another species (e.g. toad tadpoles). The methodology need an explicative figure for the device use to in the behavioral assay. In the current form is difficult to follow all the steep for each experiment. The authors used only one density of tadpoles to study the transmission of the bacterium, so how do they know the effect of tadpole aggregation in the transmission process. In the other hand sometimes large tadpoles shown aggressive behavior over the smaller tadpoles, the authors observed this pattern in the experiments? Tadpoles exposed to a patch of pebbles previously colonized by the bacterium may have no attractive for tadpoles, perhaps if the patch were colonized also by periphyton the density of acquire bacteria could be similar to the group-mate treatment For me is not surprise that large tadpole acquire more bacteria than smaller one, because the large tadpoles have major expose area, then they have more area available for colonized by bacteria. Line 188 past metamorphosis, replace by after metamorphosis, and also this paragraphs is little speculative Line 190-193 a little speculative Line 182-183 similarly is expected that more active tadpole is more exposed to visual predators, therefore the frequency of encounter with predator, parasites and bacteria is probably major in more active individuals. Here may be exist a new trade-off between acquired bacteria for protection against pathogens and exposed to visual predators. Will be interesting study how interact these variables with the presence /absence of predators. On behalf of the Editors, I am pleased to inform you that your Manuscript RSOS-191080 entitled "Tadpole body size and behavior alter the social acquisition of a defensive bacterial symbiont" has been accepted for publication in Royal Society Open Science subject to minor revision in accordance with the referee suggestions. Please find the referees' comments at the end of this email.
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Once again, thank you for submitting your manuscript to Royal Society Open Science and I look forward to receiving your revision. If you have any questions at all, please do not hesitate to get in touch. The authors (Keiser et al.) details an interesting work that tested the effect of social interaction in the transmission of a microbial symbiont in the green frog tadpoles. In some host this bacterium can confer protection against infection by Batrachochytrium a lethal pathogen that cause high level of mortality in amphibians. Clearly the results present by the authors have merits to be publish. However, I think the manuscript could be improved after some revisions that I details below Sincerely yours Is not clear in the introduction if the tadpoles of green frog are social or sub-social, i.e. they form schools or only aggregate for feeding or because they select warm sites as another species (e.g. toad tadpoles). The methodology need an explicative figure for the device use to in the behavioral assay. In the current form is difficult to follow all the steep for each experiment. The authors used only one density of tadpoles to study the transmission of the bacterium, so how do they know the effect of tadpole aggregation in the transmission process. In the other hand sometimes large tadpoles shown aggressive behavior over the smaller tadpoles, the authors observed this pattern in the experiments? Tadpoles exposed to a patch of pebbles previously colonized by the bacterium may have no attractive for tadpoles, perhaps if the patch were colonized also by periphyton the density of acquire bacteria could be similar to the group-mate treatment For me is not surprise that large tadpole acquire more bacteria than smaller one, because the large tadpoles have major expose area, then they have more area available for colonized by bacteria. Line 188 past metamorphosis, replace by after metamorphosis, and also this paragraphs is little speculative Line 190-193 a little speculative Line 182-183 similarly is expected that more active tadpole is more exposed to visual predators, therefore the frequency of encounter with predator, parasites and bacteria is probably major in more active individuals. Here may be exist a new trade-off between acquired bacteria for protection against pathogens and exposed to visual predators. Will be interesting study how interact these variables with the presence /absence of predators.

01-Aug-2019
Dear Dr Keiser, I am pleased to inform you that your manuscript entitled "Tadpole body size and behavior alter the social acquisition of a defensive bacterial symbiont" is now accepted for publication in Royal Society Open Science.
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